Astronomers Are Hunting Stupendously Large Black Holes That Dwarf Supermassive

Astronomers have detected a new class of massive black holes that dwarf even the most supermassive ones found at the center of many galaxies. The James Webb Space Telescope is giving astronomers new insights into how these extremely large supermassive black holes, known as stupendously large black holes, may have come into existence.

Most everyone is familiar with the large black hole that exists at the center of the Milky Way, Sagittarius A*. While it may appear to be massive in terms of size, it is actually quite small in comparison to many others throughout the Universe. Some are known to be 1,000 times more massive than Sagittarius A*, and large enough to span the entire width of our solar system. One in particular, Ton 618, is known to be 66 billion times the mass of Earth’s Sun, and is up to 40 times wider than the distance between Neptune and the Sun. While that may sound impossible to beat, some scientists believe there could be even larger ones.

“From a theoretical perspective, there’s no limit,” explained James Nightengale, an observational cosmologist at Newcastle University in the UK.

Black holes come in a wide range of sizes, which range from a micro black hole, the size of an atom, to ultramassive black holes, which are believed to be around 10 billion times the mass of Earth’s Sun. Astronomers spotted the first ultramassive black holes in the early 2010s, and since have found around 100 in total. Some scientists believe there could be another, even larger, class of black holes out there, known as stupendously large black holes, which could have a radius roughly a light-year across.

With the advent of the James Webb telescope, astronomers and scientists have been able to venture further back into the beginning of time. This is allowing them to detect galaxies in what they believe to be the first few hundred million years of the Universe’s existence. It is also providing evidence for something that defies much of what they believed to know about the limits on how black holes form and grow.

JWST has revealed previously unseen types of galaxies which shine brighter than expected, and believed to have existed around 600 million years to one billion years after the Big Bang. What is most surprising about them is the amount of light they emit, which seems to indicate supermassive black holes already inside them.

The fact JWST is finding black holes that are the same size as their own galaxy right so early in the history of Universe, suggests that black holes may have formed first before galaxies grew around them. Hannah Ubler, a cosmologist at the University of Cambridge in the UK, says these are “tens to a few hundred” times larger than expected. She added that astronomers refer to these early black holes as “overmassive black holes,” and it is “really surprising and really puts a challenge to theoretical models to explain how these black holes managed to grow so massive so quickly.”

While there are a few theories as to how these supermassive black holes grew to their sizes, it remains unclear how large black holes might be in the modern cosmos. Julie Hlavacek-Larrondo, an astrophysicist at the University of Montreal, remarked, “We have this rough estimate based on the age of the Universe. But Maybe the Universe will surprise us.”